1. Field of the Invention
The present invention relates to frame corner elements of tensile horizontal frame tensile structures such as tents, awnings, canopies, and the like.
2. Description of Related Art
The present invention is disclosed herein with respect to tensile frame tents; however, the scope of the invention includes all tensile frame structures employing a substantially horizontal polygonal frame comprising elongate beams that form the sides of the polygonal frame, supported by vertical posts. Examples in addition to tents include, for instance, awnings and canopies. Such structures are referred to herein generically as “horizontal frame tensile structures” or “HFTS.”
Horizontal frame tensile structure type tents are well known. The shape of such a tent as viewed from above is usually a regular polygon having n corners and n sides, where n is an integer greater than 2. At each corner is a corner element. Corner elements are generally pre-formed structures that connect frame beams and posts at each corner. Beams are the elongate, horizontal frame members that form the sides of the polygonal frame. Beams are also commonly referred to as “eaves.” Posts are vertical frame members that hold the horizontal polygonal frame above the ground or other supporting surface.
A membrane, as the term is used herein, refers to a fabric covering that is placed over the frame to provide the roof of the HFTS. In some contexts “membrane” also includes fabric sides of the HFTS. The membrane may be made of, for instance, canvas, nylon, rubberized fabrics, and the like. The type of fabric need not be specified here as it will be chosen in response to design criteria.
FIG. 1 shows a typical HFTS in the form of a square cross-cable frame tent 100. For the sake of clarity only one example each of a plurality of identical elements is shown and/or numbered. At the corners of the tent are corner elements 107, which join the beams 101 to produce the polygonal frame. Posts 102 support the polygonal frame above the ground or other surface. Typically, guys 106 secure the HFTS to the pegs 105 driven into the ground. A membrane 103 is tensioned over the frame, forming a roof. The peaks 104 of the roof in this example are supported by an internal flying pole and cable network (not shown). Other types of HFTS tents may employ a single central peak supported by a mast. The invention disclosed herein accommodates these and other types of tensile frame structures.
Although the arms and legs shown herein are depicted as hollow tubes for receiving the beams and posts, respectively, these connecting elements may take a number of cross-sectional profiles such as polygonal, ovoid, and elliptical. The arms and legs may be solid and received by hollow beams or posts. Or they may be more complex, interlocking structures. What is relevant to the present disclosure is not the form of the elements and connector mechanisms but the size of the angles formed by the connectors with respect to each other. It is these angles that determine the orientation of the beams and posts.
The corner elements typical in the art comprise a plurality of connectors for interconnecting beams and posts. There are normally two horizontal connectors that engage the ends of adjacent beams. Such connectors are referred to herein as “arms.” The connectors for posts are referred to herein as “legs.” Normally there is one post, and hence one leg per corner unit.
Each pair of arms of a corner element receives or engages the ends of two adjacent beams, maintaining the ends of the beams in fixed positions relative to one another. The interior angles of the polygonal frame formed by the arms are referred to herein as “corner angles.” In regular polygonal prior art structures the corner angles are equal and are determined by the formula: [(n−2)180]/n degrees, where n is the number of corners or number of sides. A corner angle that equals or approximates this formula is referred to herein as “standard” in order to distinguish it from canted corner angles produced by the invention as disclosed below. By way of example, standard corner angles for some common HFTS's are as follow: triangle—60°; square/rectangle—90°; hexagon—120°; octagon—135°. “Canted corner angles” as that term is used herein refers to corner angles wherein the arms are splayed such that they form a corner angle greater that the standard corner angle.
A second important angular component of the corner element is the angle between the arms and the leg. This angle, referred to herein as the “leg angle” determines the angular orientation of the post to the beams. In present art HFTS's this angle is 90°. “Canted leg angles” as that term is used herein refers to leg angles that form more than 90°.
Once the posts and beams are interconnected by means of the corner elements, a membrane is attached to the perimeter of the polygon thus formed, thereby forming the roof of the structure. In some applications the membrane may include walls attached to the beams.
FIG. 2 shows corner element 200 as commonly used in existing square or rectangular HFTS tents. The existing art corner element typically has two arms 210 and 211 for receiving beams (not shown) of the frame. Each arm has an axis, 210a and 211a, respectively. Leg 212 receives the upper end, or top, of a post (not shown), on which the corner element will be supported when the tent is assembled. The leg has its own axis 212a. 
As shown in FIG. 3, in existing corner elements, the corner angle “A” formed by arm axes 210a and 211a is standard; that is, for a rectangular or square frame the corner angle is 90°. As shown in FIG. 4 in existing corner elements, the leg angle “B” between leg axis 212a and arm axis 211a is also 90°. The leg axes of existing structures is always 90° irrespective of how many sides the polygon has.
Prior art HFTS's have a number of problems that are not associated with other types of tensile structures. Because existing HFT's have standard corner angles and leg angles, when the frame is initially assembled and unstressed, each beam is generally straight and normal to its adjacent beams; and the posts are vertical and normal to the beams. However, when such a frame becomes stressed by the weight of the canopy, walls or other tent membranes, the elongate components bend out of their original alignment and configuration, with the beams bending inward and sagging downward, as shown for beam 101 in FIG. 1. An additional source of this distortion is that in order to assemble the frame and fit the posts a certain amount of play or clearance between the corner elements and their connecting components is necessary. Once the frame is assembled, this play exacerbates the sagging of the horizontal components. As a result of the loose and sagging beams, the frame becomes deformed and the tent is susceptible to a host of problems such as:
1) Water ponding;
2) Decreased aesthetic appeal due to wrinkles in the membrane;
3) Uneven distribution of membrane stresses thereby negatively affecting the weight-bearing ability and wind performance of the structure.
4) Gaps between adjacent tents causing water to fall between the tents rather than being channelled away to the perimeter by a gutter.
5) Decreased overall stability of the structure because of uneven distribution of stress to the membrane and slack connections between slip-fit parts.
The foregoing problems are overcome by the present invention, as disclosed below.